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Recently, I read several interesting questions on the web about the relationship between IQ and general intelligence and physiological symmetry. But more importantly, what explains the correlation? Or is it even true? Because many of the world's foremost thinkers, such as Plato, and Sartre, were ugly.

Is there really a relationship between beauty (physiological symmetry) and intelligence?

3 Answers
3

In the general population there does seem to be a positive correlation between psychometrically measured intelligence and observer rated attractiveness (Kanazawa, 2011). The power of the relationship seems to be medium to low.

Two possible explanations for this relationship are:

Intelligence and physical attractiveness both depend on physical health; meaning that people who grow up unhealthily tend to be less attractive and less intelligent.

The genes for intelligence and physical attractiveness became collocated over time as more attractive people tend to mate with more intelligent people.

Actual correlation between physical attractiveness and IQ is somewhere between insignificant and mildly positive, with a slightly higher correlation for men. The correlation between physical attractiveness and perceived intelligence is more significant.

There are typically two approaches to explain this (nature vs. nurture):

From an evolutionary psychology perspective, one theory is that intelligent men are (on average) somewhat more successful, mate with more physically attractive women, resulting in offspring that are both more intelligent and more attractive than average. Evidence does support these assertions.

However, there is an alternative explanation that accounts for these findings as an environmental (rather than hereditary) effect due to a self-fulfilling prophecy. According to this hypothesis, attractive children are perceived as more intelligent, resulting in more and better opportunities for them, that lead to better education, living standards, and ultimately higher intelligence.

The heritability of IQ, based on twin studies for example, is under some dispute, but suggests that both nature and nurture are significant factors, making both approaches equally valid. The debate may be resolved by examining cultures that don't associate physical attractiveness with intelligence (Eastern), but unfortunately, most of the research has focused on cultures that do (Western).

In other words: beautiful women chose mates that are successful. And while intelligence is one factor in success (hence the mild correlation between IQ and beauty in their offspring), it is not its only cause.
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whatDec 14 '14 at 12:31

Also mate choice takes place over the whole spectrum of the population, so that not all beautiful people procreate with all successful people, but rather in every small social circle the beautiful (waitresses) marry the (more) successful (clerks), so that while the selection of success by beauty (and vice versa) is possibly widespread, its effects are distributed along the whole continuum of beauty and success and result only in a slight overall shift. Statistical analysis would have to take into account factors such as social status or geographic location (i.e. availability of partners).
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whatDec 14 '14 at 12:35

I was going to mention the halo effect, but I believe your answer is probably better. A friend of mine once put it this way: "I'm attracted to intelligent people, so I tend to perceive attractive people as being more intelligent."
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leaDec 15 '14 at 8:48

Just going by personal experience, the opposite seems to be true for me for the majority of people who, we are told by the media, are 'beautiful'. People who are physically very attractive have to work a lot harder for me to take them seriously, especially so for people who look as though a lot of effort has gone into how such people present themselves to others.

This idea of attractiveness I think is based on perceptions of beauty as inherent and/or innate, versus beauty as something synthesised - a 'product'. One being natural (and therefore possibly 'flawed'), the other not (too 'perfect').